| 摘要 |
A bail type expansion anchor for mine roofs and the like including a threaded bolt, and expander cone nut, and an expansible shell assembled together, with the shell formed from an integral blank of sheet metal having a pair of initially flat rectangular leaves bent to semi-cylindrical configuration with side edges thereof in abutment with each other to define a complete cylinder and having a bail strap of U-shaped configuration extending upwardly from the leaves and along side the cone nut. The bolt is threaded through the cone nut with the cone nut extending between the leaves of the shell, and the bail portion of the shell includes a circular top portion having a pop-out center having an interrupted circular periphery of slightly larger diameter than the bolt aligned with the bolt and connected to the remainder of the bail by frangible uncut attachment sections, designed to be broken out from the bail upon predetermined rotation of the bolt and form an aperture for passage of the bolt therethrough.
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